Systems and methods for generating power waves in a wireless power transmission system

ABSTRACT

Embodiments disclosed herein may generate and transmit power waves that, as result of their physical waveform characteristics (e.g., frequency, amplitude, phase, gain, direction), converge at a predetermined location in a transmission field to generate a pocket of energy. Receivers associated with an electronic device being powered by the wireless charging system, may extract energy from these pockets of energy and then convert that energy into usable electric power for the electronic device associated with a receiver. The pockets of energy may manifest as a three-dimensional field (e.g., transmission field) where energy may be harvested by a receiver positioned within or nearby the pocket of energy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 15/059,898, filed on Mar. 3, 2016, entitled“Systems And Methods For Generating Power Waves In A Wireless PowerTransmission System,” which claims the benefit of U.S. ProvisionalPatent Application Ser. No. 62/272,454, entitled “Systems And Methodsfor Generating Power Waves in a Wireless Power Transmission System,”filed Dec. 29, 2015, which are hereby incorporated by reference in theirentirety

U.S. Non-Provisional patent application Ser. No. 15/059,898 is acontinuation-in-part of U.S. patent application Ser. No. 14/856,337,entitled “Receiver Devices Configured to Operate with a WirelessCharging System,” filed Sep. 16, 2015 (now U.S. Pat. No. 10,312,715),which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

This application generally relates to wireless charging systems and thehardware and software components used in such systems.

BACKGROUND

Numerous attempts have been made to wirelessly transmit energy toelectronic devices, where a receiver device can consume the transmissionand convert it to electrical energy. However, most conventionaltechniques are unable to transmit energy at any meaningful distance. Forexample, magnetic resonance provides electric power to devices withoutrequiring an electronic device to be wired to a power resonator.However, the electronic device is required to be proximately located toa coil of the power resonator (i.e., within a magnetic field). Otherconventional solutions may not contemplate user mobility for users whoare charging their mobile devices or such solutions do not allow devicesto be outside of a narrow window of operability.

Wirelessly powering a remote electronic device requires a means foridentifying the location of electronic devices within a transmissionfield of a power-transmitting device. Conventional systems typicallyattempt to proximately locate an electronic device, so there are nocapabilities for identifying and mapping the spectrum of availabledevices to charge, for example, in a large coffee shop, household,office building, or other three-dimensional space in which electricaldevices could potentially move around. Moreover, what is needed is asystem for managing power wave production, both for directionalitypurposes and power output modulation. Because many conventional systemsdo not contemplate a wide range of movement of the electronic devicesthey service, what is also needed is a means for dynamically andaccurately tracking electronic devices that may be serviced by thepower-transmitting devices.

Wireless power transmission may need to satisfy certain regulatoryrequirements. The devices transmitting wireless energy may be requiredto adhere to electromagnetic field (EMF) exposure protection standardsfor humans or other living beings. Maximum exposure limits are definedby US and European standards in terms of power density limits andelectric field limits (as well as magnetic field limits). Some of theselimits are established by the Federal Communications Commission (FCC)for Maximum Permissible Exposure (MPE), and some limits are establishedby European regulators for radiation exposure. Limits established by theFCC for MPE are codified at 47 CFR § 1.1310. For electromagnetic field(EMF) frequencies in the microwave range, power density can be used toexpress an intensity of exposure. Power density is defined as power perunit area. For example, power density can be commonly expressed in termsof watts per square meter (W/m²), milliwatts per square centimeter(mW/cm²), or microwatts per square centimeter (μW/cm²).

Accordingly, it is desirable to appropriately administer the systems andmethods for wireless power transmission to satisfy these regulatoryrequirements. What is needed is a means for wireless power transmissionthat incorporates various safety techniques to ensure that humans orother living beings within a transmission field are not exposed to EMFenergy near or above regulatory limits or other nominal limits.

SUMMARY

Disclosed herein are systems and methods intended to address theshortcomings in the art and may provide additional or alternativeadvantages as well. Embodiments disclosed herein may generate andtransmit power waves that, as result of their physical waveformcharacteristics (e.g., frequency, amplitude, phase, gain, direction),converge at a predetermined location in a transmission field to generatea pocket of energy. Receivers associated with an electronic device beingpowered by the wireless charging system, may extract energy from thesepockets of energy and then convert that energy into usable electricpower for the electronic device associated with a receiver. The pocketsof energy may manifest as a three-dimensional field (e.g., transmissionfield), where energy may be harvested by receivers positioned within ornearby a pocket of energy. In some embodiments, transmitters may performadaptive pocket forming by adjusting transmission of the power waves inorder to regulate power levels based on inputted sensor data fromsensors or to avoid certain objects. A technique for identifying regionsin the transmission field may be employed to determine where pockets ofenergy should be formed and where power waves should be transmitted. Inone example, this technique may result in determination of a specificabsorption rate (SAR) value at each spatial location within thetransmission field with respect to one or more power waves radiated fromone or more antennas in the transmission field. Determination of thespecific SAR may be done by sensors coupled to, or integrated into, atransmitter. These sensors may. capture information useful for makingSAR measurements within a transmission field, and the transmitter mayuse this information in conjunction with pre-stored calculations andestimates that determine the SAR values in the transmission field basedon known propagation characteristics of the power waves produced by thetransmitter. The SAR is the rate at which electromagnetic energy fromradio frequency (RF) waves are absorbed by a human body or anotherliving being. In another example, heat-map data, which is a form ofmapping data that may be stored into a mapping memory for laterreference or computations may be used in determining where pockets ofenergy should be formed. In yet another example, sensors may generatesensor data that may identify areas that the power waves should avoid.This sensor data may be an additional or alternative form of mappingdata, which may also be stored into a mapping memory for later referenceor computation.

In an embodiment, a method of wireless power transmission comprisescalculating, by a transmitter, a specific absorption rate (SAR) value ateach spatial location within a transmission field of the transmitterwith respect to one or more power waves radiated from one or moreantennas of the transmitter; determining, by the transmitter, a selectedportion within the transmission field where the calculated SAR valuefails a pre-defined SAR value threshold; and transmitting, by thetransmitter, the one or more power waves to converge destructively atthe selected portion within the transmission field.

In another embodiment, a method of wireless power transmission includesreceiving, by a transmitter, a specific absorption rate (SAR) value ateach spatial location within a transmission field of the transmitterwith respect to one or more power waves radiated from one or moreantennas. The method further includes determining, by the transmitter, aselected portion within the transmission field where the received SARvalue is greater than a pre-defined SAR value. The method furtherincludes transmitting, by the transmitter, the one or more power wavesto converge destructively at the selected portion within thetransmission field. The method further includes transmitting, by thetransmitter, the one or more power waves to converge destructively toform a null space at remaining portions within the transmission field.

In another embodiment, a system for wireless power transmission mayinclude one or more transmitters. Each of the one or more transmittersmay include a microprocessor configured to calculate a specificabsorption rate (SAR) value at each spatial location within atransmission field of the transmitter with respect to one or more powerwaves radiated from one or more antennas, and determine a selectedportion within the transmission field where the calculated SAR value isgreater than a pre-defined SAR value. Each of the one or moretransmitters may further include one or more antenna arrays where eachof the one or more antenna arrays includes one or more antennasconfigured to transmit power waves to converge destructively to formnull space at the selected portion within the transmission field.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings constitute a part of this specification andillustrate embodiments of the invention. The present disclosure can bebetter understood by referring to the following figures. The componentsin the figures are not necessarily to scale, emphasis instead beingplaced upon illustrating the principles of the disclosure.

FIG. 1A illustrates a wireless power transmission system, according toan exemplary embodiment.

FIG. 1B shows components of a system according to an exemplaryembodiment.

FIG. 1C shows components of the system, according to the exemplaryembodiment shown in FIG. 1B.

FIG. 2 illustrates a method to form a pocket of energy in a wirelesspower transmission system, according to an exemplary embodiment.

FIG. 3 illustrates a method for forming a null space in a wireless powertransmission system, according to an exemplary embodiment.

DETAILED DESCRIPTION

Reference will now be made to the exemplary embodiments illustrated inthe drawings, and specific language will be used here to describe thesame. It should be understood that no limitation of the scope of theinvention is intended through the descriptions of such exemplaryembodiments. Alterations and further modifications of the exemplaryembodiments and additional applications implementing the principles ofthe inventive features, which would occur to a person skilled in therelevant art and having possession of this disclosure, are to beconsidered within the scope of this disclosure.

A pocket of energy used to provide power wirelessly may be formed atlocations of constructive interference patterns of power wavestransmitted by a transmitter. The pockets of energy may manifest as athree-dimensional field where energy may be harvested by receiverslocated within or proximate to the pocket of energy. In operation, thepocket of energy produced by the transmitters during pocket-formingprocesses may be harvested by a receiver, converted to an electricalcharge, and then provided to an electronic device (e.g., laptopcomputer, smartphone, rechargeable battery) associated with the receiverto operate the device or to charge the device battery. In someembodiments, multiple transmitters and/or multiple receivers may powervarious electronic devices. The receiver may be separable from theelectronic device or integrated with the electronic device.

Constructive interference may be a type of waveform interference thatmay be generated at the convergence of the power waves at a particularlocation within a transmission field associated with one or moretransmitters. Constructive interference may occur when power wavesconverge and their respective waveform characteristics coalesce, therebyaugmenting the amount of energy concentrated at the particular locationwhere the power waves converge. The constructive interference may be theresult of power waves having particular waveform characteristics suchthat constructive interference results in a field of energy or “pocketof energy” at the particular location in the transmission field wherethe power waves converge. In the case of periodic signals, such as chirpwaves or sinusoidal waves, a constructive interference pattern iscreated when the positive and negative peaks of the power waves arrivingat a specific location are synchronized. The correlated positive andnegative peaks across the waveforms add cumulatively to create acumulative waveform having a larger amplitude than each of theindividual power waves.

Destructive interference may be another type of waveform interferencethat may be generated at the convergence of the power waves at aparticular location within a transmission field associated with one ormore transmitters. Destructive interference may occur when power wavesconverge at a particular location and their respective waveformcharacteristics are opposite each other (i.e., waveforms cancel eachother out), thereby diminishing the amount of energy concentrated at theparticular location. Where constructive interference may result ingenerating pockets of energy when enough energy is present, destructiveinterference may result in generating a negligible amount of energy or“null” at the particular location within the transmission field wherethe power waves converge to form destructive interference. In the caseof periodic waves, such as chirp waves or sinusoidal waves, adestructive interference pattern results when the positive and negativepeaks of the power waves arriving at a specific location subtract fromeach other, rather than adding cumulatively, and therefore a low(ideally zero) amplitude waveform signal results.

A transmitter may be an electronic device that comprises, or isotherwise associated with, various components and circuits responsiblefor, e.g., generating and transmitting power waves, forming pockets ofenergy at locations in a transmission field, monitoring the conditionsof the transmission field, and generating null spaces where needed. Atransmitter may generate and transmit power waves for pocket-formingand/or null steering based on a specific absorption rate (SAR) valuedetermined by the transmitter at one or more spatial locations within atransmission field of the transmitter. The specific absorption rate(SAR) value may be determined by a transmitter processor, and indicatean electric power absorbed by a living tissue, such as a human body,exposed to a radio frequency (RF) wave. The transmitter may generate andtransmit, or otherwise adjust, the power waves so that the SAR value forthe RF energy at a particular location in the transmission field doesnot exceed a predetermined SAR threshold value.

A receiver may be an electronic device that comprises at least oneantenna, at least one rectifying circuit, and at least one powerconverter, which may utilize a pocket of energy for powering or chargingthe electronic device. “Pocket-forming” may refer to generating one ormore RF waves that converge in a transmission field, forming controlledpockets of energy and null spaces. A “pocket of energy” may refer to anarea or region of space where energy or power may accumulate based on aconvergence of waves causing constructive interference at that area orregion. The “null-space” may refer to areas or regions of space wherepockets of energy do not form, which may be caused by destructiveinterference of waves at that area or region.

A transmitter may determine the present SAR value of RF energy at one ormore particular locations of the transmission field using one or moresampling or measurement techniques. In some implementations, thetransmitter may be preloaded with values, tables, and/or algorithms thatindicate for the transmitter which waveform characteristics are likelyto exceed to a pre-stored SAR threshold value. For example, a lookuptable may indicate that the SAR value for a volume of space (V) locatedsome distance (D) from the transmitter receiving a number of power waves(P) having a particular frequency (F). One skilled in the art willappreciate that there could be any number of potential calculations,which may use any number of variables, to determine the SAR value of RFenergy at a particular locations.

Moreover, a transmitter may apply the SAR values identified forparticular locations in various ways when generating, transmitting, oradjusting the power waves. In some embodiments, the SAR values may bemeasured and used by the transmitter to maintain a constant energy levelthroughout the transmission field, where the energy level is both safelybelow a SAR threshold value but still contains enough RF energy for thereceivers to effectively convert into electrical power. In someimplementations, the transmitter may proactively modulate the powerwaves based upon the RF expected to result from newly formed power wavesbased upon the predetermined SAR values. For example, after determininghow to generate or adjust the power waves, but prior to actuallytransmitting the power waves, the transmitter may determine whether thepower waves to be transmitted will result in RF energy accumulation at aparticular location that either satisfies or fails the SAR threshold.Additionally or alternatively, in some implementations, the transmittermay actively monitor the transmission field to reactively adjust powerwaves transmitted to or through a particular location when thetransmitter determines that the power waves passing through oraccumulating at the particular location fail the SAR threshold. Wherethe transmitter is configured to proactively and reactively adjust powerwaves, with the goal of maintaining a continuous power level throughoutthe transmission field, the transmitter may be configured to proactivelyadjust the power waves to be transmitted to a particular location to becertain the power waves will satisfy the SAR threshold, but may alsocontinuously poll the SAR values at locations throughout thetransmission field to determine whether the SAR values for power wavesaccumulating at or passing through particular locations unexpectedlyfail the SAR threshold. In some embodiments, the transmitter may beconfigured to generate a pockets of energy or nulls at particularlocations, and thus the SAR value may be used to determine whether areasaround a pocket of energy are satisfactorily below the SAR threshold, orto determine the efficacy of the destructive interference patternsgenerating a null space.

Although the exemplary embodiments described herein mention the use ofRF-based wave transmission technologies, it should be appreciated thatthe wireless charging techniques that might be employed are not belimited to such RF-based technologies and techniques. Rather, it shouldbe appreciated that here are additional or alternative wireless chargingtechniques, which may include any number of technologies and techniquesfor wirelessly transmitting energy to a receiver that is capable ofconverting the transmitted energy to electrical power. Non-limitingexemplary transmission techniques for energy that can be converted by areceiving device into electrical power may include: ultrasound,microwave, laser light, infrared, or other forms of electromagneticenergy.

In some embodiments, control systems of transmitters adhere toelectromagnetic field (EMF) exposure protection standards for humansubjects. Maximum exposure limits are defined by US and Europeanstandards in terms of power density limits and electric field limits (aswell as magnetic field limits). These include, for example, limitsestablished by the Federal Communications Commission (FCC) for MPE, andlimits established by European regulators for radiation exposure. Limitsestablished by the FCC for MPE are codified at 47 CFR § 1.1310. Forelectromagnetic field (EMF) frequencies in the microwave range, powerdensity can be used to express an intensity of exposure. Power densityis defined as power per unit area. For example, power density can becommonly expressed in terms of watts per square meter (W/m²), milliwattsper square centimeter (mW/cm2), or microwatts per square centimeter(μW/cm2).

In some embodiments, the present systems and methods for wireless powertransmission incorporate various safety techniques to ensure that humanoccupants in or near a transmission field are not exposed to EMF energynear or above regulatory limits or other nominal limits. One safetymethod is to include a margin of error (e.g., about 10% to 20%) beyondthe nominal limits, so that human subjects are not exposed to powerlevels at or near the EMF exposure limits. A second safety method canprovide staged protection measures, such as reduction or termination ofwireless power transmission if humans (and in some embodiments, otherliving beings or sensitive objects) move toward a pocket of energy withpower density levels exceeding EMF exposure limits.

FIG. 1A illustrates a wireless power transmission system 100, accordingto an exemplary embodiment. The wireless power transmission system 100comprises a transmitter 102 that transmits one or more power waves 104from an antenna array 106. Non-limiting examples of power waves 104 mayinclude microwaves, radio waves, and ultrasound waves. The power waves104 are controlled through a microprocessor of the transmitter 102 toform a pocket of energy 112 at one or more locations in a transmissionfield, where the controller determines that a pocket of energy 112 isneeded. The transmitter 102 is further configured to transmit the powerwaves 104 that may converge in three-dimensional space to create the oneor more null spaces in the one or more locations where transmitted powerwaves cancel each other out substantially. In some implementations, thetransmitter 102 may continuously measure the specific absorption rate(SAR) values of areas within the transmission field in order to maintainconsistent energy levels throughout the transmission field. In suchembodiments, the energy levels maintained may be high enough to providepower to receivers 103 charging electronic devices 108, 110, but remainbelow a given SAR threshold value. One skilled in the art wouldtherefore appreciate that the generation of pockets of energy 112 ornulls, may not be necessary in every embodiment, as some embodiments maymaintain a uniform or substantially uniform, safe and effective energylevel throughout the transmission field. It would further be appreciatedthat the transmitter 102 may be configured to operate according to anycombination of techniques for determining the appropriate means fordelivering power waves 104 to receives 103 in a transmission field.

In some embodiments, the transmitter 102 may comprise or may otherwisebe coupled to a memory or hard disk that stores predetermined SAR valuedetermination criteria, such as algorithms, variables, tables, or othersuch information that a processor of the transmitter 102 may use todetermine the SAR value at a given location, based on thecharacteristics of the power waves being transmitted to or through thegiven location, or about to be transmitted to or through the givenlocation. The transmitter 102 may use known channel propagation modelsand empirical data on propagation losses collected prior to manufactureor prior to deployment, to calculate what the SAR may be at somedistance from the transmitter 102. For example, prior to deployment orprior to manufacture, a probe may be used to scan a volume of spaceinside a model of living tissue, or other model intended to resemble thehuman body, such as a container filled with a liquid havingnearly-equivalent characteristics of body-tissue, may be placed within atransmission field. The antenna array 106 of the transmitter 102 maytransmit power waves 104 having various characteristics that cause thepower waves 104 to be near and intersect with the model. The probe maymeasure the SAR values and RF energy levels in the proximity of themodel and/or within the model. The probe may be used to register the RFenergies and SAR values resulting from the various waveformcharacteristics, such as the amplitude, frequency, and vectorcharacteristics, of the power waves 104 transmitted by the antenna array106. The resulting SAR values and RF energies may be stored in a memoryaccessible to the transmitter 102, which may then use the pre-storeddata to determine the SAR values at locations of a transmission fieldbased on the characteristics of the power waves 104 being generated bythe transmitter 102.

The receiver 103 and the transmitter 102 may comprise a communicationscomponent 111, which may be wireless communications chips configured totransmit various types of data through a communications signal 131 thatis a distinct wireless communication channel independent from the powerwaves 104. In some cases, such as the receiver 103 of FIG. 1, thecommunications component may be embedded or otherwise integrated into anelectronic device, such as a laptop 108 or other computer, coupled tothe receiver 103 or transmitter 102. For example, the receiver 103 maybe integrated into a laptop 108, and the communications component of thereceiver 103 may include the native Bluetooth® chipset of laptop 108. Insome cases, such as the transmitter 102 of FIG. 1, the communicationscomponent may be embedded or otherwise integrated into the transmitter102 or receiver 103. In some embodiments, a communications component maybe a distinct, stand alone structure from the transmitter 102, receiver103, or any other electronic device. The transmitter 102 may transmitcommunications signals to the receiver 103 containing operationalinstructions for the receiver 103 to execute, or containing requests forpower level data or other operational data from the receiver 103.

The microprocessor of the transmitter 102 is configured to determine howthe power waves 104 should be generated and transmitted to provideenergy effectively and to avoid living beings or other sensitive objectssafely. Determining how the power waves 104 should be generated may bebased on the SAR value sampled or determined at each spatial locationwithin the transmission field of the transmitter 102 with respect to oneor more power waves 104 radiated into the transmission field from one ormore antennas of the transmitter 102. When determining how the powerwaves 104 should be generated and transmitted, the microcontroller maydetermine the physical characteristics of the power waves 104 (e.g.,frequency, amplitude, phase), and/or which antennas of the transmitter102 may be used to transmit the power waves 104. The transmitter 102 maydetermine the characteristics of the power waves 104, and/or identify asubset of the antennas to transmit the power waves 104, such that thepower waves 104 converge at a particular location in a transmissionfield to create constructive and/or destructive interference patterns.Additionally or alternatively, the microcontroller may determine thecharacteristics and/or the antennas to transmit the power waves 104,such that the power waves 104 generate a uniform or substantiallyuniform energy level throughout the transmission field or at one or moreparticular localized areas of the transmission field.

As an example, based on a particular SAR value sampled at a particularlocation in the transmission field, the microprocessor of thetransmitter 102 may select a type of waveform for the power waves 104(e.g., chirp, sinusoidal, saw tooth, stepped), select the outputfrequency of the power waves 104, the shape of the one or more antennaarrays 106, and the spacing of the one or more antennas in at least oneantenna array 106. Using one or more of these selections ordeterminations, the transmitter 100 may generate and transmit the powerwaves 104, and, as a result, the power waves 104 form the pocket ofenergy 112 at the targeted location to power one or more electronicdevices 108, 110. The microprocessor of the transmitter 102 is furtherconfigured to, based on the SAR value at each spatial location withinthe transmission field of the transmitter 102, select the outputfrequency of the power waves 104, the shape of the one or more antennaarrays 106, and the spacing of the one or more antennas in at least oneantenna array 106 to form the one or more null spaces at locationswithin the transmission field of the transmitter 102. The pockets ofenergy are formed where the power waves 104 accumulate to form athree-dimensional field of energy.

In the exemplary embodiment, the antennas of the antenna array 106 ofthe transmitter 102 are operable as the single array of one or moreantennas. But in some cases, the microcontroller may segment the arrayinto subsets operating to service multiple device or multiple regions inthe transmission field. In an embodiment, the antenna array 106 mayinclude antenna elements where the height of at least one antenna of thearray 106 may range from about ⅛ inches to about 1 inch, and the widthof the at least one antenna can be from about ⅛ inches to about 1 inch.A distance between two adjacent antennas in an antenna array 106 can bebetween about ⅓ to about 12 Lambda. For instance, in some cases, thedistance between antennas can be greater than about 1 Lambda; in somecases, the distance between antennas can be between about 1 Lambda andabout 10 Lambda; and in some cases, the distance can be between about 4Lambda and about 10 Lambda. Lambda is the wavelength of the power waves106, and may be used as a measurement for the spacing between antennasof the antenna array 106.

The transmitter 102 calculates the SAR value at each spatial locationwithin the transmission field of the transmitter 102 with respect to oneor more power waves 104 radiated from one or more antennas of theantenna array 106 in the transmission field. The microprocessor of thetransmitter 102 then compares the calculated SAR value at each spatiallocation against a threshold SAR value. For example, based on FCCregulations, a pre-defined SAR value is about 1.6 watts per kilogram(W/Kg), so the transmitter 102 may adjust the various characteristics ofthe power waves 102 to reduce the amount of energy or power accumulatingat a particular location in the transmission field, when the transmitter102 determines that the power waves 102 accumulating at the particularlocation generate constructive interference patterns of 2.0 W/Kg, andthus no longer satisfy the threshold.

In some embodiments, the transmitter 102 may generate and transmit orotherwise adjust the power waves 104 when the calculated SAR value at aspatial location does not satisfy the pre-defined SAR value threshold.The microprocessor of the transmitter 104 may be configured to determinethe characteristics for power waves 104 and/or determine from whichantennas to transmit the power waves 104, so that the power waves 104converge to form a destructive interference pattern at the particularlocation, and result in a null space having very little, negligible, orno energy accumulation at the portion in the transmission field. In someimplementations, in order to generate null spaces, the transmitter 102may generate a first set of power waves 104 that converge constructivelyto form pockets of energy 112, and then a second set of power waves 104that converge destructively to form null spaces. In some embodiments,based upon the SAR values sampled at one or more locations of thetransmission field, the microprocessor may generate and transmit, orotherwise adjust, the power waves 104 to converge constructively atcertain locations within the transmission field, and simultaneouslygenerate and transmit, or otherwise adjust, the power waves 104 toconverge destructively to form the one or more null spaces at otherlocations within the transmission field.

In yet another embodiment, when the calculated SAR value is lesser thanthe pre-defined SAR value in a selected portion of the transmissionfield, the microprocessor is configured to select the type of powerwaves 104 to transmit such that the power waves 104 convergeconstructively at the selected portion within the transmission field,and simultaneously transmit any other type of power waves 104 thatconverge destructively to form the one or more null spaces in portionsother than the selected portions in the transmission field. These powerwaves 104 may also be produced by using an external power source and alocal oscillator chip using a piezoelectric material. The power waves104 are constantly controlled by the microprocessor of the transmitter102, which may also include a proprietary chip for adjusting phaseand/or relative magnitudes of the power waves 104.

The microprocessor of the transmitter 102, may continuously orperiodically receive and/or calculate SAR value according to one or moresampling triggers or parameters. In some instances, the microprocessormay determine the SAR value for predetermined locations according to alocation sampling-interval (e.g., one-inch interval, one-footintervals). In some instances, the microprocessor may continuouslydetermine the SAR values of locations or may determine the SAR values ata given time sampling-interval. In some instances, the microprocessormay determine or receive the SAR value for locations whenever there is achange in frequency value of the one or more power waves 104. Duringsampling, the microprocessor of the transmitter 102 determines the SARvalue of the new or adjusted power waves 104 at each predeterminedlocation or at a given location sampling-interval and then compares thenew SAR values obtained for each spatial location within thetransmission field with the pre-defined SAR value threshold. Based onthe results of the comparison, the microprocessor may identify, forexample, a location within the transmission field area where thecorresponding newly-calculated SAR value no longer satisfies thepre-defined SAR value. The microprocessor of the transmitter 102 maythen manipulate the frequency, phase, amplitude, or othercharacteristics of the transmitted power waves 104, and/or the selectionof new sets of antennas or antenna arrays for the transmission of newpower waves 104 to control the transmission of the power waves 104.

The transmitter 102 may receive location data of one or more receiverswithin the transmission field of the transmitter 102. In anotherembodiment, the transmitter 102 determines location data of one or morereceivers within the transmission field of the transmitter 102. Thetransmitter 102 calculates the SAR value at each of the one or morereceiver locations and in a zone surrounding a predetermined distancefrom the one or more receivers within the transmission field of thetransmitter 102. In another embodiment, the transmitter 102 receives theSAR value at each of the one or more receiver locations, as measured andreported by the receivers, and in a zone surrounding a predetermineddistance from the one or more receivers within the transmission field ofthe transmitter 102. The microprocessor of the transmitter 102 thencompares the calculated SAR value at each of the one or more receiverlocations and in the zone surrounding the predetermined distance fromthe one or more receivers within the transmission field with apre-defined SAR value. In an embodiment, the pre-defined SAR value canbe 1.6 watts per kilogram (W/Kg). In another embodiment, the pre-definedSAR value can be any value established by the Federal CommunicationsCommission (FCC).

When the calculated SAR value at each of the one or more receiverlocations and in the zone surrounding the predetermined distance fromthe one or more receivers satisfies the pre-defined SAR value in aselected portion of the transmission field, the transmitter 102 maygenerate and transmit or otherwise adjust the power waves 104 toconverge constructively at the selected portion within the transmissionfield. In another embodiment, when the calculated SAR value at each ofthe one or more receiver locations and in the zone surrounding thepredetermined distance from the one or more receivers does not satisfythe pre-defined SAR value in a selected portion of the transmissionfield, the microprocessor is configured to generate and transmit, orotherwise adjust, the one or more power waves 104 to convergedestructively to form one or more null spaces within selected portion inthe transmission field.

In order to determine the location of the one or more receivers, thetransmitter 102 may continuously transmit the power waves 104 and acommunication signal into the transmission field of the transmitter 102.The power waves 104 may be any type of wave having any set ofcharacteristics that may provide power to the one or more receiverslocated at a given location within the transmission field. Non-limitingexamples of power waves may include ultrasonic waves, microwaves,infrared waves, and radio-frequency waves. The power waves 104 may betransmitted with a certain set of physical characteristics (e.g.,frequency, phase, energy level, amplitude, distance, direction) thatresult in the power waves 104 providing elevated energy levels at thegiven location in the transmission field. In some embodiments, thetransmitter 102 may transmit so-called exploratory power waves, whichare power waves having a power level comparatively lower than the powerlevel ordinarily used for the power waves providing power to the one ormore receivers. The exploratory power waves may be used to identify theone or more receivers, and/or used to determine the appropriatecharacteristics for the power waves 104 that will ultimately providepower to the one or more receivers in the transmission field.

The communication signal may be any type of wave used by electricaldevices to communicate data through associated protocols. Non-limitingexamples may include Bluetooth®, NFC, Wi-Fi, ZigBee®, and the like. Thecommunications signal may be used to communicate parameters used by thetransmitter 102 to properly formulate the power waves 104. Thecommunications signal may contain data describing the characteristics ofthe low-level power waves being transmitted. This data may indicate, forexample, the direction and energy level of the power waves 104transmitted along with the communication signal.

One or more antennas of the one or more receivers may receive the powerwaves 104 and the communication signal from the transmitter 102. Thepower waves 104 may have waveform characteristics that give the powerwaves 104 low-levels of power. The communication signal may contain dataindicating the characteristics of the power waves 104. When thetransmitter 102 formulates and/or transmits the power waves 104 in acertain direction or to a certain location within the transmissionfield, a communications component 111 of the transmitter 102 maygenerate and transmit data, within the communications signal 114,describing the power waves 104. For example, the communications signal114 may indicate information about the power wave, such as theamplitude, frequency, energy level, the trajectory of the power waves,and/or the desired location to which the power waves were transmitted.

In some embodiments, a receiver 103 may then respond to the transmitter102 with an indication of its location, for example, an explicitcommunication of location information or a communication indicatingreceipt of an exploratory low power wave transmission in a segment orsub-segment, and/or confirmation that the power level of saidexploratory wave exceeds a particular threshold within the transmissionfield, using the data in the communications signal as input parameters.The one or more receivers may comprise a processor configured togenerate a message for responding to the transmitter 102 with theindication of its location. The one or more receivers may be integratedinto (e.g., within a smart phone) or coupled to (e.g., a smart phonebackpack) an electronic device comprising a processor that is configuredto generate messages indicating the receiver's location when receiving alow power wave transmission. In an alternative embodiment, the one ormore receivers can determine its own location based upon characteristicsof the received power waves as indicated by the received communicationsignal, and transmit it to the transmitter 102.

In one embodiment, the one or more antennas may be fixed upon movableelements and the distance between the one or more antennas in each ofthe one or more antenna arrays is dynamically adjusted depending on alocation of portion within the transmission field where either a pocketof energy or null space has to be formed based on a comparison result ofthe calculated SAR value and the pre-defined SAR value for the givenportion. The movable elements are any mechanical actuators that arecontrolled by the microprocessor of the transmitter. The microprocessorof the transmitter determines the location of the portion within thetransmission field, and based on the location of the portion, themicroprocessor controls the movement of the mechanical actuators onwhich the antennas are mounted.

The one or more antennas of each of the one or more antenna arrays maybe configured to transmit the one or more power waves at a differenttime from each other because of the placement of the one or moreantennas. In another embodiment, the one or more antennas of each of theone or more antenna arrays may be configured to transmit the one or morepower waves at a different time from each other because of a presence ofa timing circuit that is controlled by the microprocessor of thetransmitter. The timing circuit can be used to select a differenttransmission time for each of the one or more antennas. In one example,the microprocessor may pre-configure the timing circuit with the timingof transmission of the one or more transmission waves from each of theone or more antennas. In another example, depending on a location ofportion within the transmission field where either a pocket of energy ornull space has to be formed based on a comparison result of thecalculated SAR value and the pre-defined SAR value for the givenportion, the transmitter may delay the transmission of few transmissionwaves from few antennas.

In one implementation, the transmitter may include an antenna circuitcoupled to a switch, where each of the one or more antennas in theantenna array, are adjusted or otherwise selected depending on alocation within the transmission field where power waves, a pocket ofenergy, or null space has to be formed or otherwise transmitted based ona comparison result of the calculated SAR value and the pre-defined SARvalue for the given location. In one embodiment, the antenna array isconfigured such that the power wave direction can be steered in a firstdirection by switching on a first set of antennas of the one or moreantennas, and the power wave direction of the antenna array can besteered in a second direction by switching on a second set of antennasof the one or more antennas. The second set of antennas can include oneor more antennas from the first set of antennas, or the second set ofantennas may not include any antennas from the first set. In oneembodiment, the power wave direction of the antenna array can be steeredin a plurality of directions by switching on a set of antennas from theone or more antennas for each of the plurality of directions. Theselections of antennas in the first set of antennas and the second setof antennas are based upon the distances between the antennas in thefirst set of antennas and the second set of antennas. The distances areso chosen that the power waves emerging out of the first set, second setor any set of antennas generate effective transmission of a pocket ofenergy at the desired locations.

In another embodiment, the transmitter comprises at least two antennaarrays. In one example, the at least two antenna arrays comprises afirst antenna array and a second antenna array. The microprocessor isconfigured to control the spacing between the first antenna array andthe second antenna array. The distance between the first antenna arrayand the second antenna array is dynamically adjusted, depending on alocation within the transmission field where either a pocket of energyor null space has to be formed based on a comparison result of thecalculated SAR value and the pre-defined SAR value for the givenportion. In an embodiment, the first antenna array and the secondantenna array may be flat shaped and the offset distance between the atleast two antenna arrays is 4 inches.

In another embodiment, the transmitter comprises at least two antennaarrays. In one example, the at least two antenna arrays comprises afirst antenna array and a second antenna array. It should be noted thatfor the simplicity of explanation that the first antenna array and thesecond antenna array are being described; however, more than two antennaarrays may be included in the system without moving out from the scopeof the disclosed embodiments. Each of the first antenna array and thesecond antenna array comprises one or more rows and one or more columnsof antennas configured to transmit one or more power waves. In oneexample, the first antenna array and the second antenna array are bothused for creation of the pocket of energy at the same time depending ona location within the transmission field where either a pocket of energyor null space has to be formed based on a comparison result of thecalculated SAR value and the pre-defined SAR value for the givenportion. In another example, the first antenna array and the secondantenna array are both used for creation of the null space at the sametime depending on a location within the transmission field where eithera pocket of energy or null space has to be formed based on a comparisonresult of the calculated SAR value and the pre-defined SAR value for thegiven portion. In another example, the first antenna array and thesecond antenna array are both used for creation of the pocket of energyand the null space at the same time depending on the location within thetransmission field where either a pocket of energy or null space has tobe formed based on a comparison result of the calculated SAR value andthe pre-defined SAR value for the given portion.

FIG. 1B shows components of a system 100 according to an exemplaryembodiment. The exemplary system comprises a transmitter 102 configuredto transmit one or more power waves 104 that are intended to maintain aconsistent energy level, such that SAR levels do not exceed a SARthreshold, but there may be enough RF energy for a receiver 103 tocapture and convert to electric power for an electronic device 108coupled to the receiver 103. In the exemplary embodiment, a firstlocation 105 comprises enough RF energy that the RF energy exceeds a SARthreshold; a second location 107 comprises RF energy that is uniformthrough the transmission field, and is compliant with the SAR threshold.The transmitter 102 may detect the non-compliant SAR value of the firstlocation 105 through any number of techniques. For example, thetransmitter 102 may continuously determine the SAR value of the powerwaves 104 that the transmitter 102 is generating to particularlocations, at a given distance interval. In such examples, thetransmitter 102 may determine that the first location 105, located at agiven distance from the transmitter 102, and at a particular lateralinterval, has power waves 104 being transmitted having particularcharacteristics that cause the RF energy at that location to exceed theSAR value threshold. Accordingly, the transmitter 102 may determine thatthe power waves 104 may be adjusted to maintain uniform energy levelsacross the transmission field.

FIG. 1C shows components of the system 100, according to the exemplaryembodiment shown in FIG. 1B. In FIG. 1C, the transmitter 102 may haveadjusted the power waves 104 generated and transmitted by thetransmitter 102, to mitigate the RF energy exceeding the SAR thresholdat the first location 105. As such, the RF energy of the power waves 104remains uniform throughout the transmission field.

FIG. 2 illustrates a method to form a pocket of energy in a wirelesspower transmission system, according to an exemplary embodiment.

In a first step 202, a transmitter (TX) determines SAR values for eachspatial location within a transmission field of the transmitter withrespect to one or more power waves radiated from one or more antennas inthe transmission field. For instance, in another embodiment, TXdetermines the SAR values obtained for each spatial location within thetransmission field with respect to one or more power waves radiated fromone or more antennas in the transmission field.

One having skill in the art would appreciate that SAR values may bepredetermined or modeled according to a number of waveform parameters.The models and predetermined values are stored into memory orpreprogrammed into a processor of the TX, and the waveform parametersare known to the TX as result of determining how to generate andtransmit, or otherwise adjust, the power waves. For instance, thetransmitter may determine a SAR value sample for a particular locationusing a model that uses the frequency, power level, antenna strength,and distance of one or more power waves entering the certain volume ofspace where the particular location is found. Using these known valuesand the model, the TX may determine how much power is generated by thepower waves within the volume containing the location.

In a next step 204, the transmitter compares the SAR values for eachspatial location within the transmission field with respect to one ormore power waves radiated from one or more antennas in the transmissionfield with a pre-defined SAR value. In an embodiment, the pre-definedSAR value is 1.6 watts per kilogram (W/Kg). In another embodiment, thepre-defined SAR value can be any value established by the FederalCommunications Commission (FCC).

In a next step 206, a microprocessor of the transmitter may execute oneor more software modules in order to analyze the comparison between theSAR values for each spatial location within the transmission field withthe pre-defined SAR value, and based on the analysis identify safe areawithin the transmission field. In one embodiment, the safe area is anarea within the transmission field where the calculated SAR value islesser than the pre-defined SAR threshold value.

The microprocessor will then determine the distance and size of the safearea from the transmitter, and based on the determined distance and thesize of the safe area, the microprocessor may execute one or moresoftware modules to select a power wave to be generated by the waveformgenerator, select the output frequency of the power wave, select asubset of antennas from a fixed physical shape of one or more antennaarrays that correspond to a desired spacing of antennas to form a pocketof energy at the safe area.

In one embodiment, the transmitter may adjust the power waves for thedistance and the size of the safe area. For example, the transmitter mayadjust the phase at which the transmitter's antenna transmits the power.When an optimal configuration for the antennas is identified, memory ofthe transmitter may store the configurations to keep the transmittertransmitting at that highest level. In another embodiment, thealgorithms of the transmitter based on determined distance and the sizeof the safe area from the transmitter may determine when it is necessaryto adjust the power waves and may also vary the configuration of thetransmitter antennas. For example, the transmitter may determine thepower received at the safe area is less than maximal, based on thedetermined distance and the size of the safe area. The transmitter maythen adjust the phase of the power waves.

In the next step 208, the transmitter will transmit the one or morepower waves to converge constructively at the safe area within thetransmission field to generate the pocket of energy at the safe area.

FIG. 3 illustrates a method for forming a null space in a wireless powertransmission system, according to an exemplary embodiment.

In a first step 302, a transmitter (TX) calculates SAR values for eachspatial location within a transmission field of the transmitter. Inanother embodiment, TX receives the SAR values obtained for each spatiallocation within the transmission field.

In a next step 304, the transmitter compares the SAR values for eachspatial location within the transmission field with a pre-defined SARvalue. In an embodiment, the pre-defined SAR value is 1.6 watts perkilogram (W/Kg). In another embodiment, the pre-defined SAR value can beany value established by the Federal Communications Commission (FCC).

In a next step 306, a microprocessor of the transmitter may execute oneor more software modules in order to analyze the comparison between theSAR values for each spatial location within the transmission field withthe pre-defined SAR value, and based on the analysis identify unsafearea within the transmission field. In one embodiment, the unsafe areais an area within the transmission field where the calculated SAR valuefor each spatial location within the transmission field is greater thanto the pre-defined SAR value.

The microprocessor will then determine the distance and size of theunsafe area from the transmitter, and based on the determined distanceand the size of the unsafe area from the transmitter, the microprocessormay execute one or more software modules to select a power wave to begenerated by the waveform generator, select the output frequency of thepower wave, select a subset of antennas from a fixed physical shape ofone or more antenna arrays that correspond to a desired spacing ofantennas to form null space at the unsafe area.

In one embodiment, the distance and the size of the unsafe area from thetransmitter, as calculated according to transmitter algorithms, may varyproduction and transmission of power waves by the transmitter's antennasto form null space at the unsafe area. For example, the transmitter mayadjust the phase at which the transmitter's antenna transmits the power.When an optimal configuration for the antennas is identified, memory ofthe transmitter may store the configurations to keep the transmittertransmitting at that highest level. In another embodiment, thealgorithms of the transmitter based on determined distance and the sizeof the unsafe area from the transmitter may determine when it isnecessary to adjust the power waves and may also vary the configurationof the transmitter antennas.

In the next step 308, the transmitter will transmit the one or morepower waves to converge destructively at the unsafe area within thetransmission field to form the null space. In an embodiment, the unsafearea may receive multiple power transmission signals from thetransmitter. Each of the multiple power transmission signals comprisesthe power waves from multiple antennas of the transmitter. The compositeof these power transmission signals may be essentially zero, because thepower waves add together destructively to create the null space.

In another embodiment, at least two power waves may be generated by awaveform generator of the transmitter. The at least two power wavesgenerated may have different frequencies. The change in phase of thefrequency of one of the at least two power waves may result in formationof a unified power wave. The uniform power wave may be such that it willgenerate the null space at the unsafe area in the transmission field,along with generation of the pocket of energy in areas other than theunsafe area in the transmission field.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the steps of the various embodiments must be performed inthe order presented. As will be appreciated by one of skill in the artthe steps in the foregoing embodiments may be performed in any order.Words such as “then,” “next,” etc. are not intended to limit the orderof the steps; these words are simply used to guide the reader throughthe description of the methods. Although process flow diagrams maydescribe the operations as a sequential process, many of the operationscan be performed in parallel or concurrently. In addition, the order ofthe operations may be re-arranged. A process may correspond to a method,a function, a procedure, a subroutine, a subprogram, etc. When a processcorresponds to a function, its termination may correspond to a return ofthe function to the calling function or the main function.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Those skilled in the art mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

Embodiments implemented in computer software may be implemented insoftware, firmware, middleware, microcode, hardware descriptionlanguages, or any combination thereof. A code segment ormachine-executable instructions may represent a procedure, a function, asubprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment may be coupled to another codesegment or a hardware circuit by passing and/or receiving information,data, arguments, parameters, or memory contents. Information, arguments,parameters, data, etc. may be passed, forwarded, or transmitted via anysuitable means including memory sharing, message passing, token passing,network transmission, etc.

The actual software code or specialized control hardware used toimplement these systems and methods is not limiting of the invention.Thus, the operation and behavior of the systems and methods weredescribed without reference to the specific software code beingunderstood that software and control hardware can be designed toimplement the systems and methods based on the description herein.

When implemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable orprocessor-readable storage medium. The steps of a method or algorithmdisclosed herein may be embodied in a processor-executable softwaremodule, which may reside on a computer-readable or processor-readablestorage medium. A non-transitory computer-readable or processor-readablemedia includes both computer storage media and tangible storage mediathat facilitate transfer of a computer program from one place toanother. A non-transitory processor-readable storage media may be anyavailable media that may be accessed by a computer. By way of example,and not limitation, such non-transitory processor-readable media maycomprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othertangible storage medium that may be used to store desired program codein the form of instructions or data structures and that may be accessedby a computer or processor. Disk and disc, as used herein, includecompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), floppy disk, and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes and/orinstructions on a non-transitory processor-readable medium and/orcomputer-readable medium, which may be incorporated into a computerprogram product.

1. (canceled)
 2. A method for wireless power transmission, the methodcomprising: at a transmitter configured to provide usable power to atleast one receiver within a radio frequency (RF) transmission field:transmitting a first set of one or more RF power waves within the RFtransmission field, wherein the first set of one or more RF power waveshave first characteristics and are configured to facilitate one or moreof: (i) identifying one or more receivers, (ii) determining respectivecharacteristics of RF power waves configured to provide power to the oneor more receivers in the transmission field, (iii) identifying one ormore of a sensitive object and living being; determining respectivespecific absorption rate (SAR) values for one or more spatial locationswithin the RF transmission field based, in part, on one or more of thefirst set of one or more RF power waves and a distance from thetransmitter to the one or more spatial locations, and determining that afirst spatial location of the one or more spatial locations includes afirst receiver and satisfies a pre-defined SAR value threshold; andtransmitting a second set of one or more RF power waves to the firstspatial location of the one or more spatial locations, wherein thesecond set of one or more RF power waves have second characteristics andare configured to provide usable power to the first receiver at thefirst spatial location.
 3. The method of claim 2, wherein a subset ofthe one or more spatial locations are separated by a predeterminedlateral interval, and the respective SAR values for the one or morespatial locations within the RF transmission field are further based, inpart, on respective lateral locations of the one or more spatiallocations.
 4. The method of claim 2, wherein a subset of the one or morespatial locations are separated by a predetermined distance interval. 5.The method of claim 2, wherein each spatial locations within the RFtransmission field has a respective size, and the respective SAR valuesfor the one or more spatial locations within the RF transmission fieldare further based, in part, on respective sizes of the one or morespatial locations.
 6. The method of claim 2, further comprising:determining that a second spatial location of the one or more spatiallocations, distinct from the first spatial location, does not satisfythe pre-defined SAR value threshold; and transmitting a third set of oneor more RF power waves to the second spatial location of the one or morespatial locations, wherein the third set of one or more RF power waveshave third characteristics and are configured to adjust a SAR value atthe second spatial location such that the pre-defined SAR valuethreshold is satisfied.
 7. The method of claim 6, wherein the third setof one or more RF power waves are configured to converge destructivelyat the second spatial location forming one or more null spaces that havenegligible energy accumulation.
 8. The method of claim 6, wherein thethird set of one or more RF power waves are configured to adjust the SARvalue at the second spatial location based on a respective SAR value ofanother spatial location of the one or more spatial locations that doessatisfy the pre-defined SAR value threshold.
 9. The method of claim 6,wherein the second spatial location includes one or more of a secondreceiver, living being, and sensitive object.
 10. The method of claim 2,wherein the pre-defined SAR value threshold is within a margin of errorbeyond 1.6 watts per kilogram (W/Kg).
 11. The method of claim 10,wherein the margin of error is 10%.
 12. The method of claim 2, whereinrespective characteristics of the one or more RF power waves define oneor more of a frequency, amplitude, phase, gain, and direction.
 13. Themethod of claim 2, wherein the transmitter includes a communicationcomponent, and the method further comprises: providing a communicationsignal to the first receiver; receiving from the first receiver aresponse to the communication signal, the response including firstreceiver data; and wherein determining a first SAR value for the firstspatial location is further based, in part, on the response to thecommunication signal.
 14. The method of claim 2, further comprising:determining that a third spatial location of the one or more spatiallocations, distinct from the first spatial location, includes a thirdreceiver and satisfies the pre-defined SAR value threshold; and whiletransmitting the second set of one or more RF power waves to the firstspatial location of the one or more spatial locations, transmitting afourth set of one or more RF power waves to the third spatial locationof the one or more spatial locations, wherein the fourth set of one ormore RF power waves have fourth characteristics and are configured toprovide usable power to the third receiver at the third spatiallocation.
 15. A system for wireless power transmission, the systemcomprising: one or more transmitters, each of the one or moretransmitters configured to wirelessly provide usable power to at leastone receiver within a radio frequency (RF) transmission fieldcomprising: a microprocessor configured to: transmitting a first set ofone or more RF power waves within the RF transmission field, wherein thefirst set of one or more RF power waves have first characteristics andare configured to facilitate one or more of: (i) identifying one or morereceivers, (ii) determining respective characteristics of RF power wavesconfigured to provide power to the one or more receivers in thetransmission field, (iii) identifying one or more of a sensitive objectand living being; determine respective specific absorption rate (SAR)values for one or more spatial locations within the RF transmissionfield based, in part, on one or more of the first set of one or more RFpower waves and a distance from the transmitter to the one or morespatial locations, and determine that a first spatial location of theone or more spatial locations includes a first receiver and satisfies apre-defined SAR value threshold; and one or more antennas configured totransmit a second set of one or more RF power waves to the first spatiallocation of the one or more spatial locations, wherein the second set ofone or more RF power waves have second characteristics and areconfigured to provide usable power to the first receiver at the firstspatial location.
 16. The system of claim 15, wherein the microprocessoris further configured to determine that a second spatial location of theone or more spatial locations, distinct from the first spatial location,does not satisfy the pre-defined SAR value threshold; and the one ormore antennas are configured to transmit a third set of one or more RFpower waves to the second spatial location of the one or more spatiallocations, wherein the third set of one or more RF power waves havethird characteristics and are configured to adjust a SAR value at thesecond spatial location such that the pre-defined SAR value threshold issatisfied.
 17. The system of claim 16, wherein the third set of one ormore RF power waves are configured to converge destructively at thesecond spatial location forming one or more null spaces that havenegligible energy accumulation.
 18. The system of claim 16, wherein thethird set of one or more RF power waves are configured to adjust the SARvalue at the second spatial location based on a respective SAR value ofanother spatial location of the one or more spatial locations that doessatisfy the pre-defined SAR value threshold.
 19. The system of claim 16,wherein the second spatial location includes one or more of a secondreceiver, living being, and sensitive object.
 20. A non-transitorycomputer-readable storage medium storing executable instructions that,when executed by a transmitter configured to wirelessly provide usablepower to at least one receiver within a radio frequency (RF)transmission field with at least one processor and an antenna array,cause the transmitter to: transmit a first set of one or more RF powerwaves within the RF transmission field, wherein the first set of one ormore RF power waves have first characteristics and are configured tofacilitate one or more of: (i) identifying one or more receivers, (ii)determining respective characteristics of RF power waves configured toprovide power to the one or more receivers in the transmission field,(iii) identifying one or more of a sensitive object and living being;determine respective specific absorption rate (SAR) values for one ormore spatial locations within the RF transmission field based, in part,on one or more of the first set of one or more RF power waves and adistance from the transmitter to the one or more spatial locations, anddetermine that a first spatial location of the one or more spatiallocations includes a first receiver and satisfies a pre-defined SARvalue threshold; and transmit a second set of one or more RF power wavesto the first spatial location of the one or more spatial locations,wherein the second set of one or more RF power waves have secondcharacteristics and are configured to provide usable power to the firstreceiver at the first spatial location.
 21. The non-transitorycomputer-readable storage medium of claim 20, further comprisinginstructions that, when executed by a transmitter, cause the transmitterto: determine that a second spatial location of the one or more spatiallocations, distinct from the first spatial location, does not satisfythe pre-defined SAR value threshold; and t transmit a third set of oneor more RF power waves to the second spatial location of the one or morespatial locations, wherein the third set of one or more RF power waveshave third characteristics and are configured to adjust a SAR value atthe second spatial location such that the pre-defined SAR valuethreshold is satisfied.